In healthy term neonates, how does fractional excretion of sodium (FENA) compare to adults?

• A. Similar to adults
• B. Greater than adults
• C. Less than adults
• D. Not defined

Answer: (A)

Fractional excretion of sodium reflects how the kidneys balance sodium filtration and reabsorption. In healthy term neonates, the tubular mechanisms responsible for reclaiming sodium are mature enough to resemble those of adults. This means that, under normal hydration and intake, the proportion of filtered sodium excreted in the urine is similar to adults. Keep in mind that FENA can shift with volume status or kidney injury (low in prerenal states, higher in intrinsic renal injury) and that preterm infants may show different patterns due to immaturity, but in healthy term neonates, the expectation is comparable to adults.